A photoresist pattern forming process, which is one of semiconductor device fabricating processes, coats a surface of a semiconductor wafer (hereinafter referred to as “wafer”), namely, a substrate, with a resist film, exposes the resist film in a desired pattern, and then develops the exposed resist film to form a photoresist pattern. Usually, the photoresist forming process is carried out by a photoresist pattern forming system built by combining a coating and developing system, which coats a wafer with a resist film and develops the resist film after exposure, and an exposure system.
The coating and developing system is provided with various kinds of wet processing apparatuses. The wet processing apparatus is, for example, a resist solution application apparatus which coats a wafer with a resist solution. The resist solution application apparatus is provided with resist solution application units. Each resist solution application unit is provided with a wafer holder, a splash cup surrounding a wafer held by the wafer holder to stop the splashed resist solution, and such.
The resist solution application apparatus is provided with a nozzle head for pouring a resist solution onto a wafer W. The nozzle head is supported on a support arm to form a nozzle unit. A nozzle unit mentioned in JP-A 2010-045185 is used by a plurality of resist solution application units, for example, three resist solution application units, in common. The nozzle unit moves from one to another of the resist solution application units to pour a resist solution onto a wafer W held by the wafer holder. Developing devices which process a wafer w by a developing process are the same in construction as the resist solution application units, except that the resist solution application units and the developing devices use different processing solutions, respectively, for processing wafers W.
The respective numbers of the resist solution application units and the nozzle units are different. Therefore, plurality of resist solution application units cannot process wafers if processing solution supply lines for carrying a processing solution to the nozzle unit are stopped for maintenance or if the nozzle unit cannot operate due to trouble. When a resist solution pouring time for which the resist solution is poured onto a wafer in a normal processing process is long, the nozzle unit needs to be kept for a long time at one resist solution application unit, and hence the start of other resist solution application units is delayed. Consequently, the throughput of the wet processing apparatus is low. Accordingly, there has been a demand for a resist solution application apparatus capable of executing a normal wafer processing process at a high throughput and of suppressing the reduction of throughput when components thereof malfunction or needs maintenance.